refactor formats that use a ISO-BMFF container

Author: netroy

lib/types/heif.ts

@@ -13,9 +13,14 @@ const brandMap = {
 
 export const HEIF: IImage = {
   validate(input) {
-    const ftype = toUTF8String(input, 4, 8)
-    const brand = toUTF8String(input, 8, 12)
-    return 'ftyp' === ftype && brand in brandMap
+    const boxType = toUTF8String(input, 4, 8)
+    if (boxType !== 'ftyp') return false
+
+    const ftypBox = findBox(input, 'ftyp', 0)
+    if (!ftypBox) return false
+
+    const brand = toUTF8String(input, ftypBox.offset + 8, ftypBox.offset + 12)
+    return brand in brandMap
   },
 
   calculate(input) {

lib/types/jp2.ts

@@ -1,12 +1,16 @@
 import type { IImage } from './interface'
-import { readUInt32BE, findBox } from './utils'
+import { readUInt32BE, findBox, toUTF8String } from './utils'
 
 export const JP2: IImage = {
   validate(input) {
-    if (readUInt32BE(input, 4) !== 0x6a502020 || readUInt32BE(input, 0) < 1)  return false
+    const boxType = toUTF8String(input, 4, 8)
+    if (boxType !== 'jP  ') return false
+
     const ftypBox = findBox(input, 'ftyp', 0)
     if (!ftypBox) return false
-    return readUInt32BE(input, ftypBox.offset + 4) === 0x66747970
+
+    const brand = toUTF8String(input, ftypBox.offset + 8, ftypBox.offset + 12)
+    return brand === 'jp2 '
   },
 
   calculate(input) {